Abaco- comment noted.
Ramblings follow which may be of interest.

Utilization factor= Load factor= Capacity factor.
The ratio of actual output over a period of time, to potential output if operating at full name-plate capacity over that period.

Not the same as availability which is =
time that the generator produced power over a period / length of that time period

I have 27.5% for the industry average, the range is from 20% to 50%. The figure I used is 15% is much lower since the data sources are invariably from the industry selling equipment, or from the operators claiming great performance to justify their subsidies.
The subsidies take many forms. Some are gifts of money, payments to the landowners, guaranteed purchases at high prices, and loans transferable to grants.
Guaranteed purchases- this means that whatever power is available for sale must be purchased by the power company. Must- this means that other generators have to scale back. Coal, oil, gas plants or whatever must vary to accommodate the erratic production from the wind generator, a major source of system in-efficiency not seen in figures on the wind power plant. Consider, a business model where government will buy however much your erratic machines produce, where your competitors must cut back production to match.
I think load factor should be net, not gross, that is on electricity sold not produced, as power is used internally and to get the thing spinning from standstill, especially true of the vertical axis type in this example.
As well, the average load factor should apply over the life of the turbine. The proponents claim 20,30 or 40 years for life. Experience is that few wind generators last over 15 years and there is a noticeable decline in performance over time.

Now, if readers does not like my load factor 15% figure, they are welcome to use their own.
Try 27.5% for load factor and retain the high 25c per kWh for sales. The calculation for gross revenue pa is
3.1 x 24 x 365 x 0.275 x 0.25 =$1,867
Over 15 years this is a rate of return of about minus 3% pa.

Sources- there are thousands of sources available on the net, most of them as should be expected are propaganda for the green movement. A few a bit more impartial are these:

http://www.ref.org.uk/publications/280-a...
A surprisingly frank assessment from the Renewable Energy Foundation.

http://www.rcem.eu/media/194050/michael_...
Deals with capacity exaggerations

http://www.forbes.com/sites/christopherh...
A business view of wind power.

http://www.carnwathactnow.org/the-truth-...
Explains how wind generators produce little energy but that is ok as their real function is to extract money from government.